Sharks Like to Approach Humans from Behind, Study Suggests

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Some sharks can likely tell which way humans are facing and tend
to stay out of their field of vision, typically passing by or
approaching people from the rear, new research suggests.

Although divers and shark scientists have noticed this tendency
before, it hadn't been carefully documented, said Erich Ritter, a
scientist at the Shark Research Institute in Florida. In a new
study, published in December in the journal Animal Cognition,
research volunteers kneeled on the seafloor for hours staring
straight ahead, while interactions with Caribbean reef sharks
were videotaped from above. About 80 percent of the time, reef
sharks
that came close to the subjects passed behind them.

Volunteers assumed this unusual posture and were told to remain
still so as to not give sharks clues about their body
orientation, Vitter said. But the sharks appear to have figured
out which way the person was facing anyway — and favored passing
behind the people, he added. [ 8
Weird Facts About Sharks ]

"They truly do swim up from behind, be it that they want to sneak
up or they don't want to be seen," Ritter told LiveScience. "It
doesn't mean they sneak up in a way of having a vicious thought;
mainly, they are curious but at the same time cautious."

It's unclear how the sharks are able to tell which way humans are
facing, Ritter said. Perhaps they are able to see face masks from
afar and know from previous experience with humans that this is
where their eyes are located, he said. But since humans are an
unfamiliar species to sharks, and don't resemble any shark prey
species, this comes as a surprise, Ritter said.

Ralph Collier, a researcher with the Shark Research Committee in
Los Angeles, said the study finding helps explain stories from
commercial and sport divers, who have told him tales of turning
around to find great
white sharks staring them down. It also helps explain why
most shark attacks take place from the rear, he added. Shark
attacks remain extremely rare, only killing about 10 people
globally per year.

"I think it's another piece of information that can be added to
what we know about typical
shark behavior," Collier told LiveScience.

But another researcher wasn't impressed by the paper. "I am not
persuaded that the author's thesis was proven in this study,"
said George Burgess, director of the Florida Program for Shark
Research at the Florida Museum of Natural History. "We don't know
the past history of these sharks, and whether this interaction
with humans represents a new experience," he said. In other
words, the sharks may have seen people before, and it wouldn't be
that surprising if they could recognize the masks of people and
interpret them as eyes, since prey fish also have eyes, he
said.